The present invention is directed to compositions of matter comprising a thin metallic and/or metal alloy and/or metallic oxide, nitride, carbide, silicide, boride, and/or sulfide single or multi-layer coating disposed directly upon a non-polyethylene terephthalate substrate (xe2x80x9cnon-PET substratexe2x80x9d) substrate in the absence of a carrier sheet. The preferred embodiment of the invention is a prelaminate comprising a solar-control coating deposited upon a flexible, non-PET substrate, such as polyvinylbutyral (PVB), in the absence of a carrier sheet for the coating; a method for making the prelaminate; and a laminating machine for producing the laminate.
Impact-resistant glasses, such as those used in automobile windshields, large aquariums, skylights, window-clad buildings, and the like, generally consist of one or more layers of a polymeric material (an xe2x80x9cinterlayerxe2x80x9d) laminated between two or more layers of glass. The interspersed polymeric layer functions to absorb and disperse forces which impact upon the glass, thereby providing increased impact resistance to the glass. In the event the glass laminate does break from an impact, the interspersed polymer interlayer binds the shards together so that while the glass may break or otherwise fail from an extreme impact, the glass will not shatter.
As used herein, the term xe2x80x9cprelaminatexe2x80x9d is used specifically to designate polymeric laminates whose generally intended use is to be incorporated into a finished laminated glass product. (Of course, the actual end use of the xe2x80x9cprelaminatesxe2x80x9d fabricated by the invention described herein has no bearing on the scope of the present invention.) Therefore, as used herein, the term xe2x80x9cprelaminatexe2x80x9d means a laminate comprised of one or more polymeric layers (being of the same or different polymeric material) having deposited thereon or therebetween a thin metallic and/or metal alloy, and/or metallic oxide, nitride, carbide, silicide, boride, and/or sulfide coating. Preferably, the coating is a solar-control coating. Although the composition is, of course, still a laminate, the term xe2x80x9cprelaminatexe2x80x9d is used in this fashion because the glass industry customarily uses the noun xe2x80x9claminatexe2x80x9d to refer to a finished glass product itself (as opposed to any other laminated product which might be incorporated in the finished glass product).
In recent years, interlayers have come to incorporate not only shatter-resistant properties, but also solar-control properties. Solar-reflecting window assemblies find use, for example, in automobile and architectural applications. In these uses, there is a dual objective to be accomplished by the glass laminate: 1) to manage heat loads within an enclosed structure by reflecting a portion of the infrared wavelengths of the solar spectrum which cause heating; while 2) simultaneously maintaining good visible wavelength transmissibility. These coatings are generally referred to herein as xe2x80x9csolarcontrol coatings.xe2x80x9d In general, most solar-control coatings consist of a series of thin metal and/or metal oxide layers deposited upon a flexible, optically clear substrate, most commonly PET, or deposited directly onto a glass substrate. Numerous solarcontrol coatings of varying composition and construction are described in the patent literature. See, for instance, U.S. Pat. No. 4,413,877 to Suzuki et al.; U.S. Pat. No. 4,462,883 to Hart; U.S. Pat. No. 4,488,775 to Yamamoto; U.S. Pat. No. 4,497,700 to Groth et al.; U.S. Pat. No. 4,504,109 to Taga et al.; U.S. Pat. No. 4,546,050 to Amberger et al.; U.S. Pat. No. 4,548,691 to Dietrich et al.; U.S. Pat. No. 4,799,745 to Meyer et al.; U.S. Pat. No. 4,828,346 to Jacobson et al. U.S. Pat. No. 4,834,857 to Gillery; U.S. Pat. No. 4,847,158 to Gillery; U.S. Pat. No. 4,891,113 to Criss; U.S. Pat. No. 4,973,511 to Fanner et al.; U.S. Pat. No. 5,059,295 to Finley et al.; U.S. Pat. No. 5,071,206 to Hood et al.; U.S. Pat. No. 5,201,926 to Szczyrbowksi et al.; U.S. Pat. No. 5,279,722 to Szczyrbowski et al.; U.S. Pat. No. 5,494,743 to Woodard et al.; U.S. Pat. No. 5,563,734 to Wolfe et al.; U.S. Pat. No. 5,579,162 to Bjornard et al.; U.S. Pat. No. 5,584,902 to Hartig et al.; and U.S. Pat. No. 5,589,280 to Gibbons et al.
A significant problem encountered during the manufacture of conventional solar-control prelaminates is that the layer bearing the solar-control coating (most often PET) must be permanently bonded to the PVB layers without introducing any mechanical defects such as wrinkling, orange-peeling, etc. This is quite difficult owing to the vastly different physical characteristics of PET and PVB. To satisfy the demands of the laminated glass industry, a machine which fabricates solar-control prelaminates (or any other type of prelaminate to be incorporated into a glass laminate) must do so without introducing any mechanical defects in the prelaminate. Defects such as wrinkling in the prelaminate causes unacceptable optical defects in finished glass laminates containing the prelaminate. Adding to the problem is the fact that most of the defects in the prelaminate are not detectable until the prelaminate is incorporated into a laminated glass product. Only upon inspection of the laminated glass product are the defects in the prelaminate readily detectable, in which case the finished product must be rejected, thereby adding greatly to wastage.
Smoothly bonding PVB layers to a PET layer coated with a solar-control coating is very difficult and time-consuming because PVB (the plastic which provides impact resistance to the final glass laminate) is far more temperature-sensitive, and prone to stretch than is the interspersed coated PET film which provides solar control. Because of its extreme temperature sensitivity, PVB sheeting must be handled and worked at reduced temperatures. Even then, PVB sheeting is prone to blocking (i.e., sticking to itself when rolled onto a core). Consequently, prelaminates which incorporate PVB must also be handled at reduced temperatures prior to, during, and subsequent to processing to avoid blocking of the rolled product.
In the prior art laminates, solar-control coatings are described exclusively as being deposited upon an optically clear substrate, such as PET, which is far more stiff and more temperature-resistant than is PVB. However, the present inventors have discovered a means to apply a solar-control coating (virtually any type of solar-control coating) to a substrate, such as PVB, without having to incorporate a carrier sheet in the prelaminate product. Because the vast majority of the difficulties in manufacturing solar-control prelaminates arises during the bonding of a PET carrier sheet to a PVB layer, the present invention solves a long-felt need in the industry: a means to simplify the manufacture of solar-control prelaminates and simulteously reduce wastage. Because the prelaminates of the present invention do not require a carrier sheet bearing the solar-control coating to be incorporated into the prelaminate, a troublesome step in the manufacture of solar-control laminated glass products is eliminated by the present invention.
One aspect of the invention is directed to a solar-control prelaminate comprising a polymeric substrate, preferably PVB, containing directly thereon, and in the absence of a carrier sheet, a solar-control coating. The invention is also drawing to a polymeric substrate, preferably PVB, containing directly thereon a thin metallic and/or metal alloy, and/or metallic oxide, nitride, carbide, silicide, boride, and/or sulfide coating. The invention encompasses multilayer laminates and solarcontrol prelaminates containing the same.
Another aspect of the invention is directed to a solar-control prelaminate produced by depositing a solar-control coating upon a carrier sheet and then transferring the solar-control coating from the carrier sheet to a flexible substrate to yield a substrate having the solar-control coating contained directly thereon, without the presence of a carrier sheet. The substrate may then be bonded to other layers, if desired. In the same fashion, any thin metallic, metal alloy and/or metallic oxide, nitride, carbide, silicide, boride and sulfide coating can be deposited upon a carrier sheet and then transferred to the substrate, yielding a composition of matter which lacks a carrier sheet. The invention also encompasses multilayer solar-control prelaminates containing the same.
Yet another aspect of the invention is directed to a method of fabricating a composition of matter comprising a substrate, such as PVB, to which is directly bonded a thin metallic, metal alloy, and/or metallic oxide, nitride, carbide, silicide, boride or sulfide coating in the absence of a polymeric carrier sheet. The preferred substrate is PVB and the preferred coating is a solar-control coating. The method comprises depositing a thin metallic, metal alloy, and/or metallic oxide, nitride, carbide, silicide, boride or sulfide coating onto a carrier sheet and then transfering the coating from the carrier sheet to the substrate. This yields a substrate bearing a thin coating in the absence of a carrier sheet.
A still further aspect of the invention is an apparatus to carry out the above-noted process, thereby yielding the desired composition of matter.
The invention provides many advantages not found in the prior art. Foremost, the invention provides a solar-control prelaminate product which does not require the inclusion of a polythylene terephthalate carrier sheet. This is a distinct improvement over the prior art because mating a PVB sheet to a PET sheet is a difficult, time-consuming, and error-prone task. By eliminating the need to use a PET carrier sheet, the invention greatly eases the manufacture of solar-control prelaminates.
The invention also greatly improves the manufacture of any type of polymeric structure which must bear thin metal or metal-containing (i.e., metal oxides, nitrides, carbides, etc.) layers. In the prior art, these coatings were deposited upon a polymeric substrate which could withstand the rigors of magnetron sputtering, such as PET. The PET bearing the metal or metal-containing layer(s) would then be incorporated into the final laminated structure. In the present invention, the metal or metal-containing layer(s) are still deposited upon a carrier sheet which can withstand the rigors of magnetron sputtering; however, this carrier sheet is used solely as a carrier and is not incorporated into the final product. The carrier sheet bearing the metal layer(s) is then forced into contact with a substrate, such as PVB, and then separated from the substrate. This causes the metal layer(s) to release from the carrier sheet and adhere to the substrate. In this fashion, compositions of matter such as solar-control prelaminates can be fabricated without having to mate two substrates of different physical characteristics.
The invention is also drawn to a novel apparatus for manufacturing the new product. For purposes of brevity and clarity, the description of the invention which follows refers to a machine for the manufacture of a prelaminate product wherein the thin metallic and/or metal-containing coating is released from a PET carrier sheet and deposited upon a PVB substrate. This type of prelaminate best illustrates the problems which the present invention overcomes due to the vastly different physical characteristics displayed by PVB sheeting and PET sheeting. The invention is not limited to these substrates. The reader is invited to refer to the definitions provided below to grasp the full scope of the invention.
The invention can be used to fabricate any type of flexible, polymeric laminate wherein at least one thin metal-containing coating is disposed directly upon a polymeric sheet, such as PVB, without the presence of a carrier sheet, thereby yielding a uniform, wrinkle-free polymeric sheet having a metal-containing layer uniformly and directly contained thereon.
To deposit the metal-containing coating onto the PVB substrate so that the finished prelaminate will be suitable for use in laminated glass products, it is essential that the machine heats the PVB to a suitable temperature and applies a suitable unwind resistance to the PET carrier sheet bearing the coating to be deposited and to the PVB substrate during lamination to minimize wrinkles, ripples, orange-peeling, creep, curls, and to minimize the adverse effects of non-uniform thickness in the finished product. The balance between temperature and unwind resistance must be carefully controlled to limit stretch of the PVB substrate. This is done by utilizing a novel combination of resilient rollers (urethane or rubber) and steel rollers to apply the proper pressure during lamination and by infrared (IR) feedback for heater control and proportional tension control and proportional, integral, derivative (PID) speed control on the unwind and rewind.
Properly cooling the finished product is also essential for shipping the product rolled onto a core. PVB laminates are typically shipped either as a sheet or as a roll. If shipped as a roll, the rolled product must either be refrigerated constantly to prevent blocking, or the rolled PVB product must be interleaved with a release layer to prevent blocking of the PVB to itself in successive winds on the core. The present invention is capable of rolling PVB-containing prelaminates either without an interleaving layer, or with an interleaving layer, such as polyethylene, between each PVB laminate layer to prevent fusion of the layers. Once interleaved with a release layer, PVB-containing laminates can be stored and shipped without refrigeration.